Modular Forming Tool, Modular Forming Tool Set and Method for Producing Substantially Rotationally Symmetrical Parts

ABSTRACT

Modular forming tool (1), in particular pressing tool, preferably for producing essentially rotationally symmetrical parts, comprising at least one primary tool (10), in particular a core, at least one reinforcing tube (30) and at least one auxiliary tool (50), the forming tool (1) extending along a longitudinal extension direction (L), the primary tool (10) having a workpiece machining surface (12), a sheath surface (14) and two end surfaces (16), the workpiece machining surface (12) contacting or being designed to contact a workpiece, the sheath surface (14) delimiting the primary tool (10) in a radial direction (R), wherein the end surfaces (16) delimit the primary tool (10) in the longitudinal extension direction (L), wherein the reinforcing tube (30) has an inner sheath surface (32) and an outer sheath surface (34), wherein the primary tool (10) is pressed into the reinforcing tube (30) indirectly and/or directly via the sheath surface (14), so that the primary tool (10) is secured relative to the reinforcing tube (30) in the radial direction (R), wherein the inner sheath surface (32) and the outer sheath surface (34) each have an interference fit, wherein the auxiliary tool (50) is bounded in the longitudinal direction of extension (L) by cover surfaces (56), wherein the auxiliary tool (50) is bounded outwardly in the radial direction (R) by a circumferential surface (54), and wherein the circumferential surface (54) has a clearance fit in the radial direction (R).

The invention relates to a modular forming tool and a modular formingtool set, in particular for producing substantially rotationallysymmetrical parts, such as bolts, in particular also eccentric bolts, orscrews.

Forming tool sets are already known from the prior art. They are used totransform a workpiece blank into a defined forming geometry by means of,in particular, multi-stage plastic deformation—usually by means ofnon-cutting machining. For this purpose, a workpiece blank is introducedbetween a punch and a die of the forming tool set, wherein the workpieceblank is specifically formed by the relative movement of the punch tothe die. To achieve this forming, the punch and/or die has a core, thecore directly contacting the workpiece to effect forming of thework-piece. The forces that occur during forming are usually very high,especially during cold forming. To prevent displacement of the core orcores, the forming tools of the forming tool set usually havepositioning aids which support the cores or core in the direction of therelative movement—between the die and the punch—in a force-lockingmanner with respect to it. Due to the large number of componentsinvolved and the individuality of the tools for each individual product,the dimensioning and design of the forming tools is very extensive andcost-intensive in the case of known forming tools.

It is therefore the object of the present invention to reduce the costsinvolved in the design and maintenance of forming tools and, at the sametime, to enable safe production of workpieces.

This object is solved with a forming tool according to claim 1, with amodular forming tool set according to claim 14 and by a manufacturingmethod according to claim 15. Further advantageous features andembodiments result from the subclaims, the description and the figures.

According to the invention, a modular forming tool, in particular apressing tool, preferably for producing essentially rotationallysymmetrical parts, comprises at least one primary tool, in particular acore, at least one reinforcing tube and at least one auxiliary tool,wherein the forming tool extends along a longitudinal extensiondirection, wherein the primary tool has a workpiece machining surface, asheath surface and two end surfaces, wherein the workpiece machiningsurface contacts or is designed to contact a workpiece, wherein thesheath surface delimits the primary tool in a radial direction, whereinthe end surfaces bound the primary tool in the longitudinal extensiondirection, wherein the reinforcing tube has an inner sheath surface andan outer sheath surface, wherein the primary tool is pressed into thereinforcing tube indirectly and/or directly via the sheath surfaces, sothat the primary tool is secured relative to the reinforcing tube in theradial direction, wherein the inner sheath surface and the outer sheathsurface each have an interference fit, wherein the auxiliary tool isbounded in the longitudinal direction of extension by cover surfaces,wherein the auxiliary tool is bounded radially outwardly by acircumferential area, and wherein the circumferential area has aclearance fit in the radial direction. The modular forming tool isthereby in particular a press tool, wherein the modular forming toolserves to be used in a forming manufacturing step or in a formingmanufacturing process. Preferably, the modular forming tool is used toproduce essentially rotationally symmetrical parts, such as bolts orscrews. These essentially rotationally symmetrical parts are, inparticular, parts which are preferably at least in sections rotationallysymmetrical about an axis, wherein these parts may have spiral-likeexternal contours, such as a thread, or tool engagement contours whichmay destroy or break the perfect rotational symmetry of these parts. Forexample, in this context, bolts, eccentric bolts or screws, amongothers, are substantially rotationally symmetrical parts within themeaning of the invention. In other words, the modular forming tool maybe used to form a workpiece such that a substantially rotationallysymmetrical part such as a bolt or screw is created. The modular formingtool comprises a plurality of different modules, wherein the modularforming tool comprises at least one primary tool, at least onereinforcing tube, and at least one auxiliary tool. The modular formingtool thereby extends along a longitudinal extension direction. Thelongitudinal extension direction of the forming tool is in particularthe direction in which the length of the modular forming tool isdetermined and/or around which the forming tool is built. In otherwords, the forming tool and/or the reinforcing tubes and/or theauxiliary tools and/or the primary tools may be arranged in an assembledstate in such a way that they surround or enclose the longitudinalextension direction. Alternatively or additionally preferably, thelongitudinal extension direction can also be the direction in which theworkpiece mainly extends and/or in which the forming tool moves duringthe forming of the workpiece. The primary tool of the modular formingtool is used to contact the workpiece machining surface of the primarytool with a workpiece in such a way that the workpiece is formed by thiscontact. In other words, this may mean that the workpiece machiningsurface is the surface of the primary tool that contacts or can contactthe workpiece for forming the workpiece. In particular, the primary toolis formed as a core, preferably made of hard metal. In this context, acore can be understood to mean that the primary tool is in particularsuch that, viewed in the radial direction, it at least partially formsan inner core of the modular forming tool, which is, however, preferablyhollow (e.g. tubular). In particular, therefore, the primary tool isformed in such a way that the workpiece machining surfaces and/or theworkpiece machining surface of the primary tool delimit or bound theprimary tool inwardly in the radial direction. In addition to theworkpiece machining surface, the primary tool also has a sheath surfaceand two end surfaces. The sheath surface limits the primary tool in theradial direction, in particular outwardly. In other words, this can meanthat the sheath surface forms the part of the respective primary toolfacing outward in the radial direction. In this case, the radialdirection extends perpendicular to the longitudinal extension direction.In other words, this can mean that the radial direction points radiallyaway from the longitudinal extension direction. In particular, thesheath surface of the primary tool is formed at least substantiallyrotationally symmetrical to or about the longitudinal extensiondirection. In this context, at least substantially rotationallysymmetrical means that the sheath surface is formed primarily by acylindrical surface about the longitudinal direction of extension.However, recesses or bores may be recessed or introduced in the sheathsurface, which represent a slight deviation from the ideal rotationalsymmetry, wherein a substantially rotationally symmetrical design aboutthe longitudinal extension direction of the sheath surface is still tobe given in the case of this slight deviation. In the longitudinalextension direction, the primary tool is limited by the end surfaces. Inparticular, the end surfaces are such that they have a normal which issubstantially parallel to the longitudinal extension direction. In otherwords, the end surfaces of the primary tool are substantially planar,wherein this plane in which the respective end surface lies has a normalwhich is substantially parallel to the direction of longitudinalextension. Essentially parallel in the sense of the invention are twodirections in particular if the included angle between these twodirections is at most 1° preferably at most 0.5° and more preferably atmost 0.1°. Particularly preferably, the modular forming tool has aplurality of primary tools, in particular 2, 3 or 4 primary tools, whichadvantageously can all have the features described above.Advantageously, these primary tools are designed or arranged within themodular forming tool in such a way that they each have an end surfacewhich directly contacts an end surface of a further primary tool. Inother words, this can mean that the primary tools can be arranged nextto or behind each other in the longitudinal direction in such a way thatthey make direct contact with each other. In this way, a particularlycompact modular forming tool can be achieved. Advantageously, each ofthese primary tools forms part of a core of the modular forming tool. Inaddition to the primary tool, the modular forming tool also comprises atleast one reinforcing tube. The reinforcing tube has an inner sheathsurface and an outer sheath surface. The inner sheath surface limits thereinforcement tube inwardly in the radial direction and the outer sheathsurface limits the reinforcement tube outwardly in the radial direction.It is/are expedient that the inner sheath surface and/or the outersheath surface of the reinforcing tube, preferably of all reinforcingtubes, is/are formed at least substantially rotationally symmetrical toor about the longitudinal extension direction.

Advantageously, both the inner sheath surface and the outer sheathsurface are formed at least substantially rotationally symmetrical aboutthe longitudinal extension direction. This essentially rotationallysymmetrical design of the inner sheath surface and/or of the outersheath surface of the reinforcing tube or of all reinforcing tubes ofthe forming tool can result in a particularly high mechanicalload-bearing capacity of the reinforcing tube and in the reinforcingtubes being able to be produced particularly inexpensively. The primarytool, in particular all primary tools, are pressed into a reinforcingtube via the sheath surface of the respective primary tool. For thispurpose, the sheath surface of the primary tool forms an interferencefit with an inner sheath surface of at least one reinforcing tube. Thisinterference fit between the inner sheath surface of the reinforcingtube and the sheath surface of the primary tool prevents or impedesdisplacement of the primary tool in the radial direction with a positivefit and in the longitudinal direction with a frictional fit(interference fit) relative to the reinforcing tube. Advantageously,each primary tool is pressed into a reinforcing tube in this way. Aninterference fit means that there is an interference fit between the twocontacting surfaces of the components. The interference fit prevents anydisplacement between the respective primary tool and the reinforcementtube. In an assembled or installed or mounted state of the modularforming tool, the inner sheath surface and the outer sheath surface ofthe reinforcing tubes or of the reinforcing tube of the modular formingtool are in particular designed or arranged in such a way that at leastthe inner sheath surface and, advantageously, also the outer sheathsurface in each case form an interference fit with a further component.These interference fits can, for example, be interference fits between areinforcing tube and a primary tool or, alternatively and preferably, areinforcing tube can also be pressed into a further reinforcing tube. Inaddition, preferably, a reinforcing tube can also form an interferencefit with a tool holder, in particular via the outer casing surface.Advantageously, therefore, each reinforcing tube can be press-fitted ina different component. In particular, the tool receptacle is thecomponent of the forming tool that surrounds and/or receives thereinforcing tube(s), the auxiliary tool(s) and the primary tool(s). Inparticular, the tool receptacle therefore limits the forming tool in theradial direction or radially outward. Advantageously, the toolreceptacle has an inner sheath surface which is also cylindrical and/orsubstantially rotationally symmetrical about the longitudinal extensiondirection. Advantageously, this inner sheath surface is arranged in theforming tool in such a way that it can contact, or in an assembled statecontacts, the outer sheath surfaces of the reinforcing tubes of theforming tool and/or the circumferential area of the auxiliary tools,which have the largest radial dimension. In addition to the reinforcingtube and the primary tool, the forming tool also comprises at least oneauxiliary tool, preferably a plurality of auxiliary tools. Thisauxiliary tool or the auxiliary tools of the modular forming tool havecover surfaces in the longitudinal direction of extension. In otherwords, the auxiliary tool is therefore bounded in the longitudinalextension direction by the cover surfaces, in particular completely bythe cover surfaces. Advantageously, these cover surfaces are flat and/oreach have a normal which is essentially parallel to the longitudinaldirection. In addition to the cover surfaces, the auxiliary tool alsohas a circumferential surface which delimits the auxiliary tooloutwardly in the radial direction, in particular the auxiliary tool isdelimited outwardly in the radial direction exclusively by thecircumferential surface. In other words, the circumferential surface isthe surface which limits the auxiliary tool outwardly in the radialdirection. This circumferential surface is advantageously designed to beessentially rotationally symmetrical with respect to the longitudinalextension direction, in order to achieve simple and inexpensivemanufacture of the auxiliary tool. In addition, a particularlymechanically loadable design of the auxiliary tool can also be achievedin this way. The rotary surface is designed in such a way that it has aclearance fit in the radial direction. A clearance fit in this contextmeans that the rotating surface of the at least one auxiliary tool,preferably of all auxiliary tools, has a clearance or undersize inrelation to the nominal or nominal diameter. Alternatively oradditionally preferably, a clearance fit in this context can also beunderstood to mean that the auxiliary tool has a clearance fit or aspatial clearance in relation to the part directly surrounding it in theassembled state, which can in particular be a tool holder. The auxiliarytools of the modular forming tool serve primarily to be able to absorbaxial forces in a form-fitting manner from the reinforcing tubes and/orthe primary tools during the machining operation along the longitudinalextension direction. Advantageously, the auxiliary tools themselves arein turn also held positively in the tool holder, at least in thedirection in which the machining forces act during forming of theworkpiece. This positive support of the primary tool enables the primarytools and the reinforcement tubes to be securely fixed. The clearancefit of the auxiliary tools in the radial direction ensures that therotating surface of the auxiliary tools should transmit just no shearforces, or at least only very low shear forces. The modular design ofthe forming tool, comprising primary tools, reinforcing tubes andauxiliary tools, makes it possible to achieve a particularlycost-effective and simple design, because both the reinforcing tubes andthe auxiliary tools, as well as the primary tools, have simple geometricshapes which can be assembled in a manner similar to a modular system toobtain a modular forming tool, while at the same time enabling safeproduction of the workpiece through safe positioning of the toolsurfaces.

It is expedient that the auxiliary tools and/or the reinforcement tubesand/or the primary tools are formed in one piece. In this way, it can beachieved that these components can also withstand high loads.

Advantageously, the forming tool has a tool holder, in particular anouter tool holder, with all primary tools, reinforcement tubes andauxiliary tools of the forming tool extending at least partially insidethe tool holder. The tool holder therefore forms, in particular, theradially outward bounding enclosure of the forming tool in the radialdirection. In other words, the tool receptacle can therefore serve as orform a kind of surrounding, in particular cylindrical, outer boundary ofthe forming tool. Advantageously, the tool receptacle has a continuous,in particular central, recess and/or an inner sheath surface which, forexample, may also be formed at least partially by the recess. Thisrecess or this inner sheath surface advantageously extends in thelongitudinal direction, wherein all primary tools, reinforcing tubes andauxiliary tools of the forming tool can be arranged or—in an assembledstate—are arranged within this recess or in the volume spanned by theinner sheath surface. However, it cannot be ruled out that at least someparts of the primary tools, the reinforcing tubes and/or the auxiliarytools may also be located partially outside the outer tool holder,viewed in the direction of longitudinal extension. In other words, thismay mean that advantageously each primary tool, reinforcing tube and/orauxiliary tool is located or extends at least partially—in an installedstate—within the tool receptacle, in particular within the recess and/orwithin the volume spanned by the inner sheath surface. By providing anouter tool receptacle, a particularly high mechanical load-bearingcapacity of the modular forming tool is achieved, so that a particularlysecure positioning can take place. In addition, this can also ensurethat particularly high forming forces can be safely applied to theworkpiece. The tool holder is designed in particular as a single pieceso that it can also withstand high mechanical loads. It is expedientthat at least one auxiliary tool is supported indirectly and/or directlyin a form-fitting and/or force-fitting manner relative to the toolholder, in particular in a positive and/or negative direction along thelongitudinal extension direction, in order to be able to safely absorband dissipate the high forces on the primary tools and/or the auxiliarytools that occur during forming.

Advantageously, at least one cover surface of an auxiliary tool directlycontacts a reinforcement tube and/or a primary tool. In this way, aparticularly secure form-fit positioning of the reinforcement tubeand/or the primary tool can be achieved, in particular in the directionof longitudinal extension. In addition, this can also relieve the pressfit between the primary tool and the reinforcing tube surrounding theprimary tool, so that material and/or weight can be saved on thereinforcing tubes. Direct contact in this context means that the topsurface of the auxiliary tool is intended to make direct contact withthe reinforcing tube and/or a primary tool, in particular with its endsurface.

It is expedient that at least one cover surface of an auxiliary tool isfree of reinforcement tube contact and/or primary tool contact. Free ofreinforcement tube contact and/or free of primary tool contact meansthat at least one cover surface of at least one auxiliary tool has nodirect or indirect contact with a reinforcement tube and/or with aprimary tool. The decisive factor for this determination is inparticular the assembled state of the forming tool. In other words, thisauxiliary tool can act as a mere positioning aid, similar to a reliningdisc.

Advantageously, all auxiliary tools in the modular forming tool aredesigned or arranged in such a way that they have a maximum of one coversurface which is in contact with a reinforcement tube and/or with aprimary tool. This design or arrangement of the cover surface or coversurfaces of the auxiliary tools in relation to the reinforcing tubesand/or to the primary tools ensures that the auxiliary tools are loadedin particular in only one direction, advantageously exclusively in thepositive or negative longitudinal direction. In particular, this cansave manufacturing costs, because the cover surfaces of the auxiliarytool, which are designed to be free of reinforcement tube contact and/orprimary tool contact, do not have to be manufactured to the same qualityas the cover surfaces of the auxiliary tools that make contact with thereinforcement tube and/or primary tool. Furthermore, with areinforcement tube contact-free and/or primary tool contact-freearrangement of the cover surfaces of the auxiliary tool, cost-intensivesurface treatments for reducing the surface roughness of these coversurfaces can be dispensed with or their use can at least be reduced, inparticular to reduce settling phenomena. Therefore, a particularlycost-effective modular forming tool can be achieved by the reinforcementtube contact-free and/or primary tool contact-free arrangement of thecover surface or surfaces.

Advantageously, the outer dimension of the circumferential surface of atleast one auxiliary tool essentially corresponds to the nominaldimension of the outer sheath surface of a reinforcing tube.Correspondence with the “essentially nominal dimension” is present inparticular if the outer dimension of the circumferential surface of thedecisive auxiliary tool and the outer dimension of the outer sheathsurface of the reinforcing tube have the same dimensions except for thetolerance class. Therefore, in particular, the governing outer sheathsurface of the reinforcing tube and the governing dimension of thecircumferential surface of the auxiliary tool are such that theycorrespond to the same nominal dimension, so that they differ only withrespect to their tolerance class. For example, the decisive outer sheathsurface of the reinforcing tube can have a tolerance class of m to u andthe circumferential surface of an auxiliary tool can have a toleranceclass of b to h. In particular, DIN ISO 286-1 can be decisive for thetolerance class. By designing the circumferential surface of at leastone auxiliary tool in such a way that it essentially corresponds to thenominal dimension of the outer circumferential surface of a reinforcingtube, it is possible to save expensive storage costs, because thevariety of parts to be kept in stock can be greatly reduced as a result.It is particularly preferred if the outer dimension of thecircumferential surface of all auxiliary tools substantially correspondsto the nominal dimension of the outer sheath surface of at least oneother reinforcing tube of the modular forming tool. In other words, thismay mean that the outer dimension of the circumferential surfaces ofeach auxiliary tool corresponds to at least the outer dimension of areinforcing tube of the modular forming tool, except for the toleranceclass.

Expediently, the forming tool has a plurality of reinforcing tubes,wherein the reinforcing tubes radially surround the primary tool, inparticular all primary tools. This makes it possible to achieve a simplemodular design of the modular forming tool, in which costs can be savedbecause the subassembly of reinforcement tubes and the primary tool ortools can be pre-assembled as a result. In addition, the contact surfaceor surfaces between the reinforcing tubes and the primary tool orprimary tools can also provide high modular damping of the entireforming tool, resulting in particularly good vibration characteristics.The term “surround” in the radial direction means that all the primarytools, viewed in the radial direction, have at least one reinforcingtube which surrounds the primary tool or all the primary tools.

It is expedient that at least one end surface of a primary tool, inparticular of each primary tool, is flush with a reinforcing tube in thelongitudinal direction, this reinforcing tube advantageously surroundingthe primary tool. The flush closure of the primary tool with areinforcing tube, advantageously with all reinforcing tubes thatsurround the primary tool, can save costs, because this effectivelyallows preassembly to take place. This prefabrication therefore meansthat certain submodules can already be prefabricated, so that costs canbe saved. Flush closure is understood to mean that in particular an endsurface of the primary tool and a surface bounding the reinforcing tubelie in one plane in the longitudinal direction. Advantageously, thisplane is designed in such a way that it has a normal which is at leastessentially parallel to the direction of longitudinal extension. In thisway, transverse forces acting perpendicular to the longitudinaldirection can be avoided. In other words, flush closure can therefore beunderstood to mean that at least one distal end of a primary tool and ofa, in particular surrounding, reinforcing tube lie in one plane in thelongitudinal extension direction. Advantageously, all the reinforcingtubes surrounding the primary tool are flush with this surroundedprimary tool in the longitudinal direction.

In an advantageous embodiment, at least one end surface of a primarytool, in particular of each primary tool, is flush in the longitudinaldirection with all reinforcing tubes surrounding the respective primarytool. This makes it possible to achieve simple prefabrication orpreassembly, so that assembly costs can be further reduced.

Preferably, the reinforcement tubes and/or the auxiliary tools are madeof rolling bearing steel. By designing the reinforcement tubes and/orthe auxiliary tools from rolling bearing steel, a particularlymechanically resilient design of the modular forming tool can beachieved so that even high forming forces can be safely applied to theworkpiece without the risk of mechanical failure of the modular formingtool.

Expediently, the reinforcing tubes are formed in such a way that allreinforcing tubes having substantially equal outer dimensions in theradial direction also have substantially equal inner dimension in theradial direction. In other words, this may mean that all reinforcingtubes having substantially the same dimensioned inner sheath surfacesalso have substantially the same dimensioned outer sheath surfaces. A“substantially equal” or “substantially the same” dimensioning exists inparticular if the relevant dimensions differ from each other only by amaximum of +/−0.08 mm, preferably by a maximum of +/−0.05 mm,particularly preferably by a maximum of +/−0.02 mm, and especiallypreferably by a maximum of +/−0.01 mm. For example, the reinforcingtubes, which have a cylindrical inner sheath surface and a cylindricalouter sheath surface, can be designed in such a way that the reinforcingtubes with the same diameter of the inner sheath surface also have thesame diameter with regard to the outer sheath surface. This geometricclassification of the reinforcing tubes can further increase themodularization of the modular forming tool so that costs can be saved.However, the length of these reinforcement tubes in the longitudinaldirection can be different despite the same inner and outer dimensions.Advantageously, however, the lengths of these reinforcement tubes in thelongitudinal direction are also the same.

Advantageously, at least the inner reinforcing tubes, preferably allreinforcing tubes, are designed in such a way that the ratio of theinner dimensions in the radial direction to the outer dimension in theradial direction is in a range from 0.7 to 0.98, preferably in a rangefrom 0.8 to 0.97 and particularly preferably in a range from 0.85 to0.95. The inner reinforcing tubes are in particular the reinforcingtubes which, in particular in an installed or grouted state, contactanother reinforcing tube at their outer circumferential surface.Therefore, in particular, the reinforcing tubes whose outer sheathsurface contacts the tool holder are not internal reinforcing tubes.Alternatively or additionally preferred, only those reinforcing tubesare not internal reinforcing tubes which have the largest dimension inthe radial direction. With a ratio of the inner dimension in the radialdirection to the outer dimension in the radial direction in a range from0.7 to 0.98, a particularly easy-to-manufacture geometry of thereinforcing tubes can be achieved, so that costs can be saved. A ratioof 0.8 to 0.97 results in reinforcement tubes with particularly highmechanical strength. The ratio is determined on the basis of the maximumexternal dimensions of the reinforcement tube in the radial direction tothe minimum internal dimensions of the reinforcement tube in the radialdirection.

More expediently, the modular forming tool is a punch and/or a die. Inother words, the modular forming tool can be designed both as a punchand/or be designed as a die. A die in the sense of the present inventionis a forming tool which is not moved during the forming process, but inparticular is arranged stationary in relation to the machine tool. Apunch in the sense of the invention, on the other hand, is a formingtool which is moved in relation to the machine tool and/or in relationto the die during the forming process.

Preferably, the modular forming tool is bounded in the longitudinalextension direction by a screw plug. In other words, this can mean that,viewed in the longitudinal direction, at least one screw plug forms adistal end section of the modular forming tool in the longitudinaldirection. By using a screw plug, a particularly simple and securefixing of the modular components of the forming tool can be achieved.Advantageously, the tool holder has an internal thread into which thescrew plug is screwed or can be screwed.

It is expedient for the screw plug to have a threaded section, thethreaded section having a nominal diameter which is greater than themaximum dimension of all the reinforcing tubes of the forming tool inthe radial direction. Due to this particularly large design of thethreaded section of the screw plug, a particularly high mechanical loadcapacity can be achieved. The nominal diameter of the threaded sectionis in particular the outer diameter of the thread. Particularlypreferably, the nominal diameter of the thread is 1.1 to 1.4 times themaximum dimension of all the reinforcing tubes of the forming tool inthe radial direction. This makes it possible to achieve both amechanically loadable and compact design of the thread section. In thiscontext, the decisive maximum dimension of all reinforcement tubes ofthe forming tool in radial direction is the largest possible dimensionin radial direction of the reinforcement tubes of the decisive modularforming tool. In other words, the maximum dimension of all thereinforcement tubes of the forming tool in the radial direction may bethe maximum outer diameter of the largest reinforcement tube. Therelevant modular forming tool is in particular the die or the punch onwhich the screw plug is mounted.

Another aspect of the invention may relate to a modular forming toolset, which may comprise two modular forming tools according to theabove-described embodiments, wherein the one modular forming tool is apunch and wherein the second modular forming tool is a die.

A likewise further aspect of the invention relates to a method forproducing substantially rotationally symmetrical parts, in particularscrews and/or bolts, comprising the steps: Providing a workpiece blankand forming the workpiece blank by a modular forming tool as describedabove and/or below. The forming of the workpiece blank is therebyeffected by contact of the workpiece blank with the work-piece machiningsurface(s) of the primary tool(s) of the modular forming tool. Theforming of the workpiece blank into a substantially rotationallysymmetrical part may thereby be accomplished by only one forming step.Alternatively preferably, however, several forming steps may beperformed in the manufacturing process. In this case, it is preferred ifeach of these forming steps is carried out using a modular forming toolaccording to the invention. After or before the forming of the workpieceblank, further processing steps may also be included in themanufacturing process, such as recutting and/or rolling of a threadand/or the application of lubricants, in order to simplify the formingof the workpiece blank.

Further advantages and features of the invention will be apparent fromthe following description in relation to the figures. Showing:

FIG. 1 a section through a modular forming tool in the form of a die;

FIG. 2 a section through a modular forming tool in the form of a punchand

FIG. 3 a modular forming tool set.

FIG. 1 shows a modular forming tool 1, which is a die 3. The formingtool 1 extends along the longitudinal direction L, wherein the radialdirection R extends radially away from this longitudinal direction L.The forming tool 1 comprises a tool holder 60 as well as numerousprimary tools 10 and reinforcing tubes 30. The forming tool 1 comprisesa tool holder 60 as well as numerous primary tools 10 and reinforcingtubes 30. In addition, the forming tool 1 also has two auxiliary tools50. One of the auxiliary tools 50 at least partially forms a distal endof the forming tool 1 along the longitudinal extension direction L byone of its cover surfaces 56. The tool holder 60 has an inner peripheralsurface which forms an interference fit with the outer sheath surfaces34 of the outer reinforcing tubes 30. In contrast, the auxiliary tools50 and their circumferential surface 54 have clearance fits with respectto the tool holder 60 and the inner sheath surface of the tool holder60, respectively. The reinforcing tubes 30 are each mechanically fixedin place via their inner sheath surface 32 and via the outer sheathsurface 34 by means of an interference fit, so that this interferencefit counteracts a displacement in the direction of longitudinalextension L. The reinforcement tubes 30 closest to the longitudinaldirection of extension L in the radial direction R or the centralreinforcement tubes 30 each at least partially enclose an auxiliary tool50. These auxiliary tools 50 are pressed into the inner sheath surface32 of the closest central reinforcement tube 30 via their sheath surface14. Through this, a fixation of each primary tool 10 in radial directionR and at least partially also in longitudinal extension direction L canbe achieved. The end surfaces 16 of the primary tools 10 each form thedistal ends of the primary tools 10 in positive and/or negativelongitudinal extension direction L. In an assembled state, as shown inFIG. 1 , these end surfaces 16 can either be arranged in a contact-freemanner or can be arranged in a contacting manner with an auxiliary tool50 and/or a further end surface 16 of a primary tool 10, thecontact-free end surfaces 16 forming in particular a distal end of theforming tool 1. Radially inward in radial direction R, the primary tools10 each form a workpiece machining surface 12. The primary tool 10 canin particular be formed from a hard metal, while the reinforcing tubes30 and/or the auxiliary tools 50 can be formed from rolling bearingsteel. As can be seen from FIG. 1 , the primary tools 10 and thereinforcing tubes 30 each form a press connection to one another via thecontacting sheath surfaces 14 of the primary tools 10 and the innersheath surfaces 32 of the reinforcing tubes. The auxiliary tools 50, onthe other hand, do not have any interference fit, so that they are notheld in any way by an interference fit in the longitudinal direction ofextension L. Rather, there is a clearance fit between thecircumferential surface 54 of the auxiliary tool 50 and the tool holder60.

FIG. 2 shows a modular forming tool 1 in the form of a punch 2. Thepunch 2 has a primary tool 10 which is enclosed by the reinforcing tubes30. The reinforcing tubes 30 each have an inner sheath surface 32 in theradial direction R towards the inside, which forms an interference fitwith the adjacent or nearest surface. In addition to the reinforcingtubes 30 and the primary tool 10, the punch 2 also has a number ofauxiliary tools 50, which serve to provide positive support for theprimary tools 10 and the reinforcing tubes 30 in the direction of thelongitudinal extension direction L. These auxiliary tools 50 each have acircumferential surface 54 which delimit the respective auxiliary tool50 in radial direction R. These circulating surfaces 54 each have aclearance fit with their outer surrounding or contact partner in theradial direction R. In addition to the primary tools 10, the auxiliarytools 50 and the reinforcing tubes 30, the punch 2 also has a screw plug70 which forms a distal end of the punch 2 along the longitudinaldirection of extension L.

The screw plug 70 has a threaded section 72 that has a nominal diameterthat is greater than the maximum dimension of all of the reinforcingtubes 30 of the punch 2.

FIG. 3 shows a forming tool set comprising a forming tool 1 in the formof a punch 2 and a forming tool 1 in the form of a die 3. The punch 2and die 3 shown in FIG. 3 may correspond to the punch 2 in FIG. 2 andthe die 3 in FIG. 1 , respectively. During a forming process of aworkpiece to be formed by means of the forming tool set, the punch 2 canbe moved in relation to the die 3 along the longitudinal extensiondirection L in order to achieve forming of the workpiece. For thispurpose, in particular, the free space F inside the punch 2 can be usedto form the head of a bolt or screw. In other words, by displacing partof the material of the workpiece within the free space F and/or into thefree space F, the head of the workpiece, in particular that of a screwand/or a bolt, can be created. The primary tools 10 are also used toachieve the configuration of the workpiece, such as a thread and/or ahead and/or a shank of a substantially rotationally symmetricalcomponent. In this respect, the auxiliary tools 50 are each arrangedover their circumferential surface 54 in such a way that these have aclearance fit in the radial direction R.

LIST OF REFERENCE SIGNS

1—Forming tool

2—Punch

3—Die

10—Primary tool

12—Workpiece machining surface

14—Sheath surface

16—Face

30—Reinforcing tube

32—Inner surface

34—Outer sheath surface

50—Auxiliary tool

54—Circulation area

56—Cover surface

60—Tool holder

70—Screw plug

72—Threaded section of the screw plug

F—Free space

L—Longitudinal direction of extension

R—Radial direction

1. Modular forming tool (1), in particular press tool, comprising atleast one primary tool (10), in particular a core, at least onereinforcement tube (30) and at least one auxiliary tool (50), whereinthe forming tool (1) extends along a longitudinal extension direction(L), wherein the primary tool (10) has a workpiece machining surface(12), a sheath surface (14), and two end surfaces (16), wherein theworkpiece machining surface (12) contacts or is adapted to contact aworkpiece, wherein the sheath surface (14) bounds the primary tool (10)in a radial direction (R), wherein the end surfaces (16) delimit theprimary tool (10) in the longitudinal extension direction (L), whereinthe reinforcing tube (30) has an inner sheath surface (32) and an outersheath surface (34), wherein the primary tool (10) is pressed into thereinforcing tube (30) indirectly and/or directly via the sheath surface(14), so that the primary tool (10) is secured relative to thereinforcing tube (30) in the radial direction (R), wherein the innersheath surface (32) and the outer sheath surface (34) each have aninterference fit, wherein the auxiliary tool (50) is limited in thelongitudinal extension direction (L) by cover surfaces (56), wherein theauxiliary tool (50) is bounded outwardly in the radial direction (R) bya circumferential surface (54), wherein the circumferential surface (54)has a clearance fit in the radial direction (R), and wherein the modularforming tool (1) is a punch.
 2. Modular forming tool (1) according toclaim 1, wherein the forming tool (1) has an outer tool holder (60),wherein all of the primary tools (10), reinforcing tubes (30) andauxiliary tools (50) of the forming tool (1) extend at least partiallywithin the tool holder (60).
 3. Modular forming tool (1) according toclaim 1, wherein at least one cover surface (56) of an auxiliary tool(50) directly contacts a reinforcing tube (30) and/or a primary tool(10).
 4. Modular forming tool (1) according to claim 1, wherein at leastone cover surface (56) of an auxiliary tool (50) is free ofreinforcement tube contact and/or primary tool contact.
 5. Modularforming tool (1) according to claim 1, wherein the outer dimension ofthe circumferential surface (54) of at least one auxiliary tool (50)substantially corresponds to the nominal dimension of the outer sheathsurface (34) of a reinforcing tube (30).
 6. Modular forming tool (1)according to claim 1, wherein the forming tool (1) comprises a pluralityof reinforcing tubes (30), wherein the reinforcing tubes (30) surroundthe primary tool (10), in particular all primary tools (10), in theradial direction (R).
 7. Modular forming tool (1) according to claim 1,wherein at least one end surface (16) of a primary tool (10), inparticular of each primary tool (10), terminates flush in thelongitudinal extension direction (L) with a reinforcing tube (30). 8.Modular forming tool (1) according to claim 1, wherein at least one endsurface (16) of a primary tool (10), in particular of each primary tool(10), terminates flush in the longitudinal extension direction (L) withall reinforcing tube(s) (30) surrounding the respective primary tool(10).
 9. Modular forming tool (1) according to claim 1, wherein thereinforcing tubes (30) and/or the auxiliary tools (50) are made ofrolling bearing steel.
 10. Modular forming tool (1) according to claim1, wherein the reinforcing tubes (30) are formed such that allreinforcing tubes (30) having substantially the same outer dimension inradial direction (R) also have substantially the same inner dimension inradial direction (R).
 11. Modular forming tool (1) according to claim 1,wherein at least the inner reinforcing tubes (30), preferably allreinforcing tubes (30), are formed such that the ratio of the innerdimension in radial direction (R) to the outer dimension in radialdirection (R) is in a range of 0.7 to 0.98, preferably in a range of 0.8to 0.97 and particularly preferably in a range of 0.85 to 0.95. 12.Modular forming tool (1) according to claim 1, wherein the modularforming tool (1) is limited in longitudinal extension direction (L) by ascrew plug (70).
 13. Modular forming tool (1) according to claim 1,wherein the screw plug (70) has a threaded section (72), wherein thethreaded section (72) has a nominal diameter that is between an innerdimension and an outer dimension of a reinforcing tube (30) of theforming tool (1).
 14. Modular forming tool set comprising two modularforming tools (1) according to claim 1, wherein the one modular formingtool is a punch (2), and wherein the second modular forming tool (1) isa die (3).
 15. Method of manufacturing substantially rotationallysymmetrical parts comprising the steps: Provision of a workpiece blankand Forming the workpiece blank by a modular forming tool (1) accordingto claim 1.